In international patent application PCT/FR 89/00546, filed in the name of THOMSON-CSF, an especially powerful method of transmission has been described which uses a multicarrier modulation of OFDM type enabling a digitized signal to be transmitted with a high density. In the method of transmission described, a plurality of orthogonal frequencies are used and a pair (amplitude-phase) or (real part, imaginary part) is transmitted on each frequency, the amplitude-phase or real part-imaginary part pair being the one-to-one equivalent of the item of information to be forwarded. In order to produce the above one-to-one function, use is made of a constellation in a known manner. Indeed, each sub-carrier constituting the signal is modulated in amplitude and in phase in a discrete manner and the discrete positions, in amplitude and in phase, constitute a constellation in the complex plane. Several types of constellation can be used. Thus, in international patent application PCT/FR 89/00546 a circular constellation has been proposed. In this case, the amplitude-phase pairs corresponding to each digital word are distributed uniformly over concentric circles. The transcoding between the binary words of the digitized signal and a point of the constellation can be done in many ways without using any especially simple relationship. However, it is important for this encoding to make it possible to avoid, during reception, the maximum number of errors at the signal recovery level.
Thus, the aim of the present invention is to offer a novel method of binary encoding the points of a constellation which makes it possible to limit the number of errors during decoding.